Preheat your oven to 375°F (190°C).

In a mixing bowl, combine the cooked rice, diced onion, diced celery, dried cranberries, chopped walnuts, parsley, salt, pepper, and garlic powder.

Stuff each Cornish hen with the rice mixture, packing it gently.

Using kitchen twine, tie the legs of the hens together.

Place the stuffed hens breast-side up in a roasting pan and brush with melted butter, seasoning with additional salt and pepper.

Roast in the preheated oven for about 1 hour until the internal temperature reaches 165°F (74°C).

Remove the hens from the oven and let them rest for 10 minutes before serving.

Carve the hens and serve with the stuffing on the side.